Sin (Knight and the Flames #1)

Sin is Book #1 in the Knight and the Flames series by Beth Sweetlake, a co-written name by established authors, Elizabeth Knox, Iris Sweetwater and Rae B. Lake.

I was a feared and loved white knight until the day I fell from grace...
I came to the realm of the Unseelie Court to complete my duty and slay the corrupt king, but once I saw her, my mission changed.
I had to have her.
Locked in a cage of magical making, she was the epitome of chaos and destruction. Everything that I was supposed to be against.
But my heart, my soul, and my body crave her.
But my craving could turn my white wings black and complicate a war that has been raging for centuries.
Is she worth more death?
I don't know if I care anymore.